Europe saw the barricades go up in capitals across the continent in the revolutions of 1848. The discontents of 1968 burst forth in turbulent fashion across the United States and Europe.

Now Brazil has joined a list of nations subject to surprising popular uprisings. The list goes back to the “cedar revolution” in Lebanon, the abortive “green revolution” in Iran, and the Arab spring and its bitter fruit, the Syrian civil war.

Lately, protesters in Turkey have challenged the heavy hand of Recep Tayyip Erdogan, the prime minister. Brazil has followed, with a million protesters taking to the street this week.

Turkey and Brazil are two of the world’s rising powers. They have experienced rapid economic growth, lifting millions of people out of poverty and into an expanding middle class. The trouble they are experiencing used to be called the “revolution of rising expectations” — revolutions reflecting the impatience of newly empowered citizens making new demands on old elites.

Brazilians are disgusted with the billions of dollars being spent on deluxe soccer facilities in anticipation of the World Cup soccer tournament. These expenditures are occurring even as everyday public services lag behind. Proposed hikes in bus fees apparently touched off the anger that millions of ordinary Brazilians feel about the corruption and incompetence of their leaders.

Could it have been the self-immolation of a street vendor in Tunisia that sparked this chain of events? That was the catalyst that began the uprising that led to the ouster of the autocratic and corrupt president of Tunisia, who chose not to put up much of a fight. It was a few months later that throngs of Egyptians packed into Tahrir Square in Cairo, which yielded the departure of Egypt’s corrupt autocrat, Hosni Mubarak.

Revolution does not follow a tidy script. Repression in Bahrain quashed an uprising there (with minimal protest from the United States, which maintains an important naval base there). It has not been tidy in Libya, where the United States and its allies thwarted repressive measures by Moammar Gadhafi, leading to his overthrow and death. Lack of order in Libya has spawned the dispersion of jihadi ideology and Libyan weaponry.

The most horrific chapter in this new story of public outrage has been the civil war in Syria, where President Bashar Assad is fomenting sectarian warfare, drawing in Shiite allies from Lebanon, Iraq and Iran to battle Sunni rebels supported by Saudi Arabia, Qatar and the West.

Turkey and Brazil, modern nations with histories of repression and corruption, are not Syria or Libya. They are democracies where the public is getting a whiff of its own power. The trouble encountered by the leadership of these countries is the price inevitably exacted from those who pursue the interest of a narrow minority at the expense of the majority. For the sake of people in both countries and for the stability of their regions, one hopes the leadership is responsive to the people.

Past revolutionary eras have led to years of reaction. The revolution of 1848 in France produced the reign of a new emperor. Turmoil in the United States in 1968 led to Richard Nixon. Reactionary, neo-fascist elements are seething around the edges of politics in Greece, Italy and other European nations, where people are reaching the conclusion that the powers that be are in collusion against them.

Democracy and participation are the best avenues toward justice, but when people reach the conclusion that the avenue is blocked, they take to the streets. That is what the Tea Party and Occupy Wall Street have been about. The Tea Party has been more successful politically because conservatives have been willing to engage in politics. It is a fluid, volatile, unpredictable time. When Brazilians are protesting soccer, you know things are askew.